This invention relates to a new delivery system for flavors and to the process for its preparation, which has use in a variety of products including comestibles such as chewing gum compositions, confections, pharmaceuticals, food products such as beverages and some baked goods, dentifrice compositions and denture adhesives and in packaging applications. More particularly, this invention relates to a process for preparing a flavor delivery system which facilitates the delivery of higher levels and intensity of flavor without the harshness or off notes that is experienced at higher flavor concentrations.
Flavor delivery systems are well known in the art which may be divided into various classes based upon their physical states, namely, liquids, emulsions, pastes or solids. Not only are these states different but the potential uses for each state also differ as do their method of manufacture.
Over the years considerable effort has been directed toward the preparation of flavoring materials. Specifically, flavor materials have been sought that provide greater flavor intensity coupled with sustained flavor release for long periods of time.
An outgrowth of this activity has been the observation that when free flavor oil is added to gum base, only about 5% to 40% of the initial flavor oil is released from the gum upon chewing. It appears that as much as 80% of the remaining flavor oil becomes irreversibly bound to the gum base and cannot be chewed out.
To overcome this difficulty with flavor oils in particular, various attempts have been made to encapsulate the flavor oils or use dried ingredients to inhibit the gum base binding action. In addition, considerable effort has been directed to the development of delayed release flavoring agents that will delay release of the flavoring agent while permitting uniform release of the flavor over an extended period of time. The obvious benefit of immediate/delayed release is the ability to provide uniform flavor sensation during the entire consumption period which has not been previously attainable by the direct incorporation of conventional seasonings and flavor oils into chewing gum formulations.
Spray drying is one of the most widely used techniques for encapsulating or fixing a flavor. In this procedure a flavor oil is usually blended with a film forming agent dispersed in water and then emulsified to form a stable emulsion. Emulsification is necessary because flavor oils are insoluble in the water needed to dissolve the film forming agent. Obtaining an emulsion of low viscosity, at high solids content, is critical to producing an acceptable product. Stability at higher temperatures is also critical to avoid volatilization of the flavor oil. Maintaining low inlet temperatures (i.e. around 155.degree. C.) as well as minimizing the residence time in the dryer are beneficial if the flavor is chemically unstable. The air drying conditions depend on the emulsion and product characteristics such as particle size of the product required. Modifications to the use of heat to remove the water from the emulsion have also been attempted. Some of these include the use of a dehydrating solvent as the drying medium rather than hot air. Freeze drying has also been contemplated.
Flavor fixation has also been obtained by the extrusion method wherein the flavor oil is coextruded with a water soluble sugar or sugar mixture, dried and ground for use. These products find application in dry mixes for instant release of the flavor on contact with water. Such products generally contain 10 to 15% by weight of flavor oil.
An extensive discussion of the prior art with respect to the extension of flavor is found in Wei et al U.S. Pat. No. 4,590,075. The patentees discuss the preparation of encapsulated flavors which are added together with a quantity of a non-confined hydrophobic flavor oil to a suspension agent before formulation in a chewing gum (Marmo et al. U.S. Pat. No. 3,920,849); the encapsulation of flavor in high molecular weight material such as polyvinyl acetate (Ogawa et al. U.S. Pat. No. 3,826,847); the preparation of a flavor composite by crosslinking the flavor with a water-insoluble hydrophilic polymer such as hydroxyethyl acrylate (U.S. Pat. No. 3,761,286); and the preparation of microencapsulated flavor particles and their dispersion in a slurry on the surface of a chewing gum (U.S. Pat. No. 3,962,463). Further, Yang et al. U.S. Pat. No. 4,695,463 is noted and discloses a flavor delivery system that relies on the immobilization of the flavor within a crosslinked hydrocolloid multivalent alginate or carageenate matrix.
Further, Sharma et al. U.S. Pat. No. 4,597,970 prepares a delivery system for actives such as sweeteners and including flavors which utilizes a hydrophobic matrix comprising edible fatty acids or waxes, lecithin and a glyceride component. This system is urged to provide a protective barrier and controlled release characteristics to the active so contained. The combination of materials in the encapsulating matrix provides wetting capabilities with respect to non-uniform core materials such as aspartame, while providing improved heat stability and thereby, extended high temperature processing capability. These attributes were frequently achieved at a cost of delay in release of the active.
Darragh et al. U.S. Pat. No. 3,867,556 also encapsulated volatile flavors in a fat or wax material. The patentees had found that the initial or base encapsulation displayed excessive instability to heat, and as their product was intended primarily for incorporation into baked goods, they applied a second coating of a water-soluble material such as gum arabic, which would provide high temperature stability while conferring rapid disintegration on contact with moisture. The Darragh et al. product likewise exhibited delayed flavor release.
Further, Merritt et al. U.S. Pat. Nos. 4,515,769 and 4,386,106 both to disclose the encapsulation of flavor material in a partially hydrophilic matrix comprising gelatin, a natural gum (or albumin as disclosed in the '769 Patent) or a plasticizer. This combined encapsulant was placed in an emulsion with the flavoring agent and thereafter dried to a solid matrix which was then ground to a base powder. The base powder was then coated with a water-insoluble material which purported to prevent flavor loss and delay flavor release in contact with moisture. Merritt et al. sought only to achieve a burst of flavor when the physical mastication of their flavor composite ruptured the outer encapsulating material. Merritt et al. may also be consulted in cumulative fashion for their review of the literature relevant to their invention.
Bakal et al. U.S. Pat. No. 4,087,557 relates to the incorporation of an artificial sweetener directly into the ester gum component of a chewing gum base, to achieve a delay and corresponding extension in sweetener release (column 2, lines 31-42). The patent contemplates the incorporation of certain flavors, specifically, food acids such as tartaric acid, succinic acid, etc. directly into the ester gum component, however, indicates that conventional flavors such as flavor oils are added separately after the gum base constituents including the artificial sweetener containing-ester gum have been mixed with each other and cooled. The flavor component is incorporated into chewing gums prepared in accordance with the patent in the conventional fashion, i.e., by direct incorporation of artificial flavor and/or by the incorporation of flavor coated with a hydrophilic material such as gum arabic (see Bakal et al., Example 6). Bakal et al. accordingly offers no solutions to the problems of flavor delivery and extension of concern to the art.
Other approaches to the preparation of flavor composites, particularly with flavor oils, are noted. Thus, Swisher U.S. Pat. No. 3,041,180 discloses a process for extruding a flavor oil with glycerine and corn syrup solids to form an encapsulated extruded flavor oil. The solid was dried and yielded a particulate solid. Miller et al. U.S. Pat. No. 4,610,890 discloses another process for preparing an extruded flavor oil with sugar, a starch hydrolysate and an emulsifier.
Yang U.S. Pat. Nos. 4,448,789 and 4,569,852 discloses a novel flavoring agent--hydrophilic polymer--by blending the flavor with the polymer and blending while heating to prepare a homogenous product. Once coupled and ground, the product can be used as a flavoring for chewing gum and confectionery products.
Giel U.S. Pat. No. 4,271,202 relates to a spray-drying process for forming solid flavoring material capable of including high percentages of flavoring oil per total particulate unit of weight. Because of the high oil content possible, such spray-dried products found wide use in a number of beverages and other foods. However, it was also found that spray-dried flavors prepared by this and similar known methods typically exhibit a relatively limited shelf life. In addition, the high temperatures necessarily involved during spray-drying processes have been found to impair the flavor and aroma of various heat-sensitive oil flavors, such as those in citrus fruit. Furthermore, solids formed by spray-drying commonly exhibit hygroscopic characteristics making them difficult to handle and store.
In addition to these techniques, Gergely U.S. Pat. No. 4,452,821 is directed to a confectionery product, especially a chewing gum, that purports to offer prolonged, extended delivery of flavoring aroma and/or active pharmaceutical ingredient. This is accomplished by providing the flavoring, aroma or active pharmaceutical ingredient in a solid solution or mixture within a wax containing functional groups, said wax forming a homogeneous mixture of solid solution. The wax does not contain any functional groups and is substantially immiscible with the flavoring, aroma or active pharmaceutical ingredient.
The approaches to flavor modification discussed above all fall short of providing a flavor delivery system which achieves the advantages of flavor intensity and fullness inherent in flavor oils in combination with improved release and extension characteristics. In most instances, where a modified flavor of this type is incorporated into a chewing gum composition, the gum base and, in particular, the elastomer component sequesters the flavor and thereby prevents its release during the chew. Moreover, the plasticizers and softeners conventionally employed in gum formulations tend to increase moisture pickup and corresponding flavor migration and loss, so that the flavor that might be available for release on chewing is further diminished in content and resulting extent of release and sensation.
It can accordingly be seen from the foregoing discussion that a broad variety of techniques, including the formation of spray-dried particles from the combination of flavor oils with hydrophilic film forming materials, have been tried, but have resulted in products of limited acceptability. If high levels of flavor oil are incorporated, the resulting particles yield an excessively harsh and bitter taste sensation, and off notes are experienced. Conversely, the reduction of the flavor intensity to avoid such bitterness, reduces the concentration of flavor in the particles so that an undesirably large quantity of particles must be added to a particular product to provide the desired flavor sensation. Finally, regardless of which of these approaches is followed, the longevity of the flavor sensation is undesirably limited.
In commonly assigned co-pending application Ser. No. 452,660, a sweetener delivery system is disclosed which employs a multiple coating system based upon an inner or core coating of the primary or first sweetener, and a second outer coating prepared from a solution of a hydrophilic polymer having a quantity of a sweetener dissolved therein. The core may be prepared from hydrophobic or hydrophilic materials, while the outer coating is primarily a hydrocolloid. The system in this instance was developed to offer protection and improved up front delivery to difficultly processible intense sweeteners such as aspartame, and provides the advantages of protection of the primary active coupled with improved up front and long term delivery performance.
The present invention seeks to adapt the attributes of the sweetener delivery system of application Ser. No. 452,660 to the instance of flavors, to respond to the need for the development of a flavor delivery system which improves flavor intensity, presentation, longevity and release in combination with greater stability and protection of the active.